> If these namespaces could only be setup by root, we would not really be any worse off, but since people are so fascinated by the "my admin won't let me do X, so I'm going to figure out a way to do it anyway" problem that they are giving too much power to non-root users.
The problem with that (only making security features available to root) is that then prorgammers can't use them. For example, 0install needs to unpack archives it downloads. Since tar may contain bugs, we'd like to run tar in a restricted environment (e.g. a chroot where /home doesn't exist). If that requires root, then 0install itself has to be setuid, which is not good.